This invention relates generally to twin roll casters, and more particularly to casting rolls for a twin roll caster.
The twin roll method of continuous casting thin metal strip from molten metal between a pair of counter rotating casting rolls and through the gap between the rolls is known for directly producing strip from molten metal. FIGS. 6 and 7 show an example of a prior art continuous casting machine, the casting rolls 2 are in contact with side dams 1 at the circumferential end surfaces of the casting rolls 2, and having hollow stub shafts 3 that axially engage the two ends of the casting rolls 2 (see for example U.S. Pat. No. 6,241,002).
The two end portions of the casting rolls 2 are smaller than the central portions, and are shaped as to come into contact with the side dams 1. In the continuous casting machine, the pair of casting rolls 2 are disposed lateral to each other in such a manner that the casting roll gap may be adjusted according to the thickness of the strip S that is to be manufactured. The side dams 1 are respectively in contact with the end surfaces of the central portion of greater diameter of the casting rolls 2 containing the molten metal M. The speed and direction of revolution of the casting rolls are set such that the outer circumferential surfaces should move towards the casting roll gap at the same speed.
Radially below and spaced from the position of the side dams, the casting rolls 2 have in the past had internally a plurality of axially extending cooling channels 4 positioned equidistantly circumferentially, and a plurality of radially extending cooling channels 5 connected with the ends of the cooling channels 4. The cooling channels 4 extend from one end of the casting rolls to the other end of the casting rolls radially below the position of the side dams. Bolts 7 or plugs 6 in the ends served as plugs to close the ends of the cooling channels 4. The radial cooling channels 5 extend from an inner circumferential surface of the casting roll at right angles to the cooling channels 4.
Radial cooling channels 8 pass through the hollow shaft 3 to allow cooling water W to flow through one hollow shaft 3 into one radial cooling channels 5, then into cooling channels 4, corresponding radial cooling channels 5 at the other end of the casting roll 2, and finally into the interior of the other hollow shaft 3.
In such a continuous casting machine, heat is removed by cooling water W flowing through the radial cooling channels 5 and the longitudinal cooling channels 4 while molten metal M is poured into the space confined by the side dams 1 and the casting rolls 2 forming a pool of molten metal M above the nip between the casting rolls. As the casting rolls rotate, the metal that is being cooled on the outer circumferential surfaces of the casting rolls 2 forms solidified shells, and strip S is sent downwards from the casting roll gap. The rate of cooling of the molten metal is however limited by the heat conductivity from the circumferential surfaces to the cooling channels.
Thus, it is apparent that it would be advantageous to provide an alternative apparatus and method to provide more efficient casting of melt strip. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.